In the course of constructing concrete slabs and the like, liquefied concrete comprised of aggregate, cement, water and other additives is freshly poured into a form and must first be brought to a desired shape and size of the slab. This is conventionally done by screeding or striking off (i.e. spreading, distributing and leveling) the uncured concrete usually with the use of prepositioned guides or rails. Typical screeding or striking methods include manually passing the edge of a two by four plank across the poured concrete as well as using powered vibratory screed devices. Much effort and time is taken by laborers during the screeding or striking process to achieve an initial flatness of the poured concrete.
Following the striking off process, the stiff fresh concrete is next worked by using a float or similar device to provide a smooth, homogenous mixture. Floating the concrete enables further settling the concrete aggregate in the poured mass and permits densifying and compacting the viscous mixture. Floating also helps remove air voids and gaps caused by the striking process and brings excess water and fine aggregates to the surface for subsequent finishing. Floating serves the purpose of driving the suspended gravel downwards, and developing a wetted surface layer or cream/paste composed of fine particles (sand, cement, fly ash) and water which is conducive to filling in the voids and gaps and preparing the surfaces for final finishing.
A bull float is most often used for the floating process in compacting and smoothing the concrete. The bull float is a working device in the form of a large rectangular plate or blade of magnesium or aluminum which is coupled to an elongated, cylindrical handle for pushing and/or pulling the plate over the top surface of the concrete. If there are spots on the slab from poor striking or low slump mixes, the bull float is shaken vigorously across those spots to achieve flatness and fill in the voids. When bull floating is done manually, it is extremely labor intensive and much strain is felt upon the operator's body.
The floating can be accompanied by some sort of a vibration of the concrete to expedite the finishing process. In one type of device, a vibrating mechanism is placed inside the elongated handle of the float tool as well as on the bull float itself. An inherent consequence of this device is that the handle vibrates as much or more than the plate of the bull float. Other devices solely employ vibrating units spaced along the upper surface of the bull float plate, but this limits the versatility of the finishing tool. In older devices, the provision of the vibratory units on the bull float surface created a heavy finishing tool which could sink into the concrete causing depressions in the surface.
Accordingly, it is desirable to provide a more versatile vibratory concrete finishing tool which will alleviate the shortcomings and problems of prior art devices. It is also desirable to provide a concrete finishing tool which will transmit vibrational energy to the working device attached to the elongated handle. It is further desirable to provide a concrete finishing tool which will provide vibrational energy to a variety of working devices attached to the elongated handle. Moreover, it is desirable to provide a vibratory concrete finishing tool having a weight which will not cause depressions in the surface of the wet concrete.